Both rear O2 sensors go through a rubber grommet in the floor and into the passenger compartment the four wire gray connector is located up by the center console toward the radio, you have to remove the sill panel at the door it just pulls up and of and lift the front carpets up not such a big job. Autozone have some popular workshop manuals for free on line once you register (for free) on their website http://bit.ly/autozone_repair_info .There is a company that independent auto repair shops "buy" their information from that offer a very reasonable service to do it yourselvers. You get a one year subscription to year make and model specific repair procedures, service bulletins, component locations, wiring diagrams ect.... great quality information same as the professionals have ,much better than generic workshop manuals from parts stores, much cheaper than the factory manual. http://bit.ly/alldata_repair_manuals or try http://bit.ly/mitchell_repair_manuals_online and get an online repair manual subscription.